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Journal of Petroleum Science & Engineering
Elsevier Science B.V.
Journal of Petroleum Science & Engineering

Elsevier Science B.V.

0920-4105

Journal of Petroleum Science & Engineering/Journal Journal of Petroleum Science & Engineering
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    A decision support engine for infill drilling attractiveness evaluation using rule-based cognitive computing under expert uncertainties

    Qiangqiang MaoYuhe WangXiaohua Ma
    15页
    查看更多>>摘要： Optimally drilling new wells in a developed reservoir is an essential strategy to potentially tap remaining oil for a complete life circle of oilfield development. Further, the determination of optimal infill drilling targets is a challenging issue which involves the integration of data, experts' knowledge and human decisions. The decision process can be essentially regarded as a systematic evaluation of drilling attractiveness. To automate drilling attractiveness evaluation, we develop a decision support engine using rule-based cognitive computing to rank and recommend drilling candidates. Such drilling candidates are chosen by the quantification of regional drilling attractiveness. Then we use two cases with different settings to show its general applicability and human-like reasoning abilities. The reasoning process considers expertise and human-involved uncertainties. The expertise is characterized by certain representation of fuzzy rules sets. Our results highlight the potential of our recommendation engine in pinpointing the most productive drilling location. And our method avoids the expensive reservoir simulation runs. Moreover, fuzzy drilling attractiveness evaluation can serve as an alternative initialization method of model-based infill well optimization, which avoids local optimum problem and greatly saves iteration time. Our approach extends human's reasoning capability and accelerates human's decision-making process with very low computational cost.
      原文链接:
    • NSTL

    A review on measurement of the dynamic effect in capillary pressure

    Ying LiChang LiuHaitao Li
    11页
    查看更多>>摘要： Studies have shown that multiphase flows in porous media are in a transient state with the dynamic effect in capillary pressure. The ignorance of the dynamic effect in capillary pressure might lead to some potential errors in engineering application. In this paper, recent advancements in the measurement of dynamic effect in capillary pressure are reviewed, focusing on the experimental setup, experimental method, and data interpretation method. The measuring technologies are developed both in accuracy and measurement range of porous media and fluids. State-of-the-art measurement technology can measure the dynamic effect in capillary pressure in tight rock and carbonate even with the existence of supercritical fluids. During the measurement process, it is essential to record the pressure difference between the wetting and the non-wetting phases and the in-situ fluid saturation. Besides, the end effect and the rapid change in the pressure at the flowing front need to be prevented. The fluid saturation can be measured through electrical resistivity under various injection pressures, which is applicable to determine the dynamic capillary pressure. The semipermeable elements are particularly the key material for testing the dynamic capillary pressure. Their installation site changes from the ends to the sides of the porous media domain. Additionally, the widely used mass balance-based method is not suitable to obtain the average fluid saturation for less permeable porous media, and calibration is required if the centroid-corrected phase average method and the intrinsic phase average method are used to compute the average dynamic capillary pressure. This paper suggests a reference for the evaluation of multiphase and unsaturated flow in porous media.
      原文链接:
    • NSTL

    Methane/CO2 binary gas interaction on some moist, high-volatile bituminous Indian coals: 2. Pure-/mixed-gas adsorption modelling

    Atanu ChatterjeeSantanu BhowmikPratik Dutta
    11页
    查看更多>>摘要： The pure and mixed methane and CO2 excess experimental adsorption of three moist, high-volatile bituminous Indian coal samples at 40 °C and up to a pressure of ～6500 kPa, were tested for the applicability of the adsorption models. For pure gas, Langmuir and Dubinin-Astakhov (DA) models were used and it was observed both Langmuir and DA models were matching with experimental data, although the fit with DA model was better. For mixed gas, Extended Langmuir (EL) and Ideal Adsorbed Solutions (IAS) theory were considered for model prediction. Later, the IAS theory was also combined with the Langmuir, DA equation for their applicability on mixed gas modelling. It was observed that none of the models were suitable for predicting the mixed gas adsorption. Although, EL-model show the maximum match for fitting experimental data at lower pressure, the deviation was increased at higher pressures. In general, the experimental CO2 separation factor was observed to decrease with an increase in pressure and CO2 gas concentration. However, the model prediction of CO2 separation factor was only validated by IAS-DA, other models showed inconsistent results.
      原文链接:
    • NSTL

    Performance evaluation of a novel CO2-induced clean fracturing fluid in low permeability formations

    Azizullah ShaikhCaili DaiYongpeng Sun
    17页
    查看更多>>摘要： After the limitations of polymer-based fracturing due to poor clean-up property during flowback after fracturing treatment, viscoelastic surfactant (VES) received very huge attention in the last three decades, especially in low permeability reservoirs. In this study, a Novel CO2-induced clean fracturing fluid (SDS-TMTAD-CO2) is formulated with simulated formation water (23,003 mg L~(-1)) after optimization experiments according to the proposed parameters (i.e., 70 °C, economical, easily preparation, and environment-friendly). The results of rheological experiments show that the apparent viscosity of the fracturing fluid system increases to a certain extent under high salt conditions and possesses sufficient self-healing property against high shear tolerance. At different temperatures (25, 50, and 70 °C), the thermodynamic properties, fluid viscoelasticity, and proppant carrying capacity meet the requirements of the fracturing fluid industry standards. After adding kerosene (0.02 mol L~(-1)); the gel breaking fluid viscosity (3.2 mPa s), anti-swelling rate (91.3%), and interfacial tension (2.3 x 10~(-2) mN m~(-1)) are holding promising conditions during the flowback period, clay swelling, and residual oil saturation, respectively. The filtration and core damage experimental results meet the national industry standard for fracturing fluids. The SEM results show that the fluid system after reaction forms a unified adsorption film on the core surface. Hopefully, this fluid system will be proved as a good candidate by means of excellent proppant transportation ability, anti-swelling, easy gel structure breaking, low filtration, and less formation damage in low permeable formations with an increase in productivity.
      原文链接:
    • NSTL

    3D visualization of tectonic coal microstructure and quantitative characterization on topological connectivity of pore-fracture networks by Micro-CT

    Kaizhong ZhangShilu WangLiang Wang
    15页
    查看更多>>摘要： Research on the connectivity characteristics and topological relationships of pore-fracture networks is crucially significant for systematic understanding the microstructure evolution on original and tectonic coals. From the aspects of digitization, visualization, non-destruction, topologization and quantitation, Micro-CT is adopted to characterize the microstructure of original, tectonic and reconstructed coals. The results indicate that the roughly vertical distribution among cleat system in original coal microstructure regularly splits coal matrix into several cubic blocks. Tectonism induces the fundamental transformation on microstructure, associated with well-developed micro-fractures and sporadic pores distributed in spatial scale. With external stress loading, the internal micro-fractures of reconstructed coal sharply decline and gradually evolves into widely-distributed pore connectivity with locally disorderly and dispersed micro-fractures. Following morphological thinning algorithm, skeletonization models were created to demonstrate that the mean tortuosity of original coal has the highest value of 1.2213, followed by reconstructed and tectonic coals of 1.1741 and 1.1205, respectively. Based on skeletonization, the topological 'ball-rod' model and its quantitative connectivity parameters reveal that the equivalent structure of pore space for tectonic coal significantly increases, compared to original coal; however, the reconstructed coal after stress loading decreases slightly to 37.75%. Tectonism may facilitate coal micro-structure to generate a high coordination number >10, enhancing the connectivity of tectonic coal; nevertheless, the coordination number of reconstructed coal dropped dramatically due to stress loading. Based on the mentioned above, the pore-scale flow simulation of micro-topological equivalent PNMs was conducted for discovering that pressure distributions of tectonic coal in different directions are more concentrated and uniform than original coal while the latter has a non-uniform flow pattern due to its structural anisotropy and heterogeneity. The aforementioned results have guiding significance for revealing the micro-topological connectivity of pore-fracture network in coal, as well as the pore-scale fluid transporting visualization.
      原文链接:
    • NSTL

    A 3D tortuous fracture network construction approach to analyze proppant distribution in post-fractured shale

    Jiaxiang XuRui GaoLifeng Yang
    15页
    查看更多>>摘要： To reveal the proppant transport in the tortuous fracture network, a method introducing the normal distribution random function into the quartet structure generation set was proposed to construct the three-dimensional tortuous fracture networks. The tortuosity can be controlled by the variance of random function. And then, the proppant distribution in the tortuous fracture network was simulated with the consideration of the interact between slurry, fracture surface and proppants. Finally, effects of velocity and viscosity of slurry and the density and particle size of proppants on the proppant distribution in three different fracture networks were investigated. The accuracy of this model was verified by the experiment. The simulation reveals that besides the velocity decrease due to the fluid split, the slurry velocity also fluctuates because of the fracture width variation. The transport distance of proppants in tortuous fracture is about 10.7% shorter than that in the smooth fracture, while the distribution height is increased in the tortuous fracture network. Instead of forming the regular sand dune, the proppant is dispersively distributed in the tortuous fracture network. The proppant density and the slurry velocity are the main factors influencing the proppant distribution, followed by the slurry viscosity and proppant size. Proppant with smaller particle size can enter the area with narrow fracture width, so that the distribution of proppant in the fracture is more uniform. The research results can provide some guidance for the optimal design of slurry and pumping schedule in the hydaulic fracturing operation.
      原文链接:
    • NSTL

    Inversion based on deep learning of logging-while-drilling directional resistivity measurements

    Jianbao FanWenxiu ZhangWenxuan Chen
    6页
    查看更多>>摘要： Because of the response complexity and real-time interpretation required by geosteering, an efficient and reliable inversion method for logging-while-drilling (LWD) directional resistivity measurement is important. A three-layer parametric inversion method based on deep learning has been developed. The inversion process includes two steps. The first step is the inversion of formation parameters, such as the resistivity and distance to boundary, and the second step is the uncertainty estimation of the inversed parameters, to remove the low-quality inversed boundaries. The input of the first part of the inversion is the directional resistivity logging data. The input of the second step is the output of the first step. The second step is based on the relationship between the output error and the value of each output parameter of the first step. A synthetic example shows the original results of the first step of the inversion have some low-quality false boundaries, such as some of the ones in thick layers. By estimating the uncertainty and distinguishing the low-quality boundary in the second step, these false boundaries can be effectively removed.
      原文链接:
    • NSTL

    Optimization of lipopeptide biosurfactant production by Bacillus licheniformis L20 and performance evaluation of biosurfactant mixed system for enhanced oil recovery

    Qi LiuJianjie NiuYajie Liu
    10页
    查看更多>>摘要： Biosurfactant is an important amphophilic microbial product, which plays an important role in microbial enhanced oil recovery (MEOR) by reducing crude oil-water interfacial tension (IFT), emulsification and wettability alternation. Compared with chemical surfactants, biosurfactants have the advantages of lower toxicity and higher biodegradability, but the relatively low yield also limits their applications. In this study, the influence of hydrocarbon carbon sources on the production of biosurfactants by Bacillus licheniformis L20 was investigated, and the variable of unit biosurfactant concentration was proposed to optimize the biosurfactant production medium. The highest concentration was obtained in LB/MSS-K medium, which was up to 1.225 g/L. The biosurfactant produced by Bacillus licheniformis L20 in that medium was characterized as lipopeptide via using FTIR. This biosurfactant shown stable emulsifying properties for different hydrocarbons and crude oils, but it can not reduce the oil-water IFT significantly. However, after mixed biosurfactant with chemical anionic surfactants (1,3-diacylglycerols-2-sulfate) and nonionic surfactant (fatty alcohol-polyoxyethylene ether), the anionic surfactant/ biosurfactant mixed system can reduce the crude oil-water IFT to 0.109 mN/m. In addition, the emulsification stability of the biosurfactant mixed system were determined, the results shown that the emulsion formed by the nonionic surfactant/biosurfactant mixed system or the anionic surfactant/biosurfactant mixed system can remain stable under a wide range of temperature, pH and NaCl concentration, respectively. Furthermore, the performance of chemical surfactant/biosurfactant mixed system were evaluated, the results shown that anionic surfactant/biosurfactant mixed system and nonionic surfactant/biosurfactant mixed system can increase the oil recovery rate by 24.12% and 21.67% respectively after water flooding, while the biosurfactant used alone was only 19.58%. Thus, the results obtained from this work shown that anionic surfactant/biosurfactant mixed system have good prospect of application in ex-situ MEOR.
      原文链接:
    • NSTL

    Comparison between conventional and NMR approaches for formation evaluation of presalt interval in the Buzios Field, Santos Basin, Brazil

    Thais Mallet de CastroWagner Moreira Lupinacci
    13页
    查看更多>>摘要： Brazilian presalt account for more than 70% of petroleum production in the country. More than ten years after the announcement of its discovery, presalt carbonates remain presenting many challenges regarding their reservoir's characterization. Well log analysis and formation evaluation of carbonate rocks are difficult tasks due to the complex and heterogeneous nature of these rocks and its associated mineral phases such as magnesian clays (Mg-clays). This study proposes a new workflow for presalt reservoirs formation evaluation that incorporates nuclear magnetic resonance (NMR) logs in the estimation of petrophysical properties such as clay volume, porosity, water saturation and net pay. This workflow aims to be useful for initial assessments when a limited amount of data is available. We compare this approach with conventional methods widely applied in formation evaluation to verify the impact that use of different methodologies can have in the final assessments. These methods are applied in Barra Velha and Itapema formations of the Buzios Field, Santos Basin. Our results show that a hybrid method which combines NMR and conventional logs for clay content and water saturation is more robust for estimation of those properties in Barra Velha and Itapema formations. Clay content based on gamma-ray logs is more assertive to represent the shales observed in the Itapema Formation. However, clay content based on NMR logs is essential to properly identify Mg-clays in the Barra Velha Formation. Regarding the water saturation, the use of only Archie's equation can result in net pay regions below the oil-water contact if their parameters were not properly determined. An accurate determination of these parameters requires a huge amount of data and measurements that are not always available. So, the hybrid approach for water saturation shows that the use of NMR logs above tire transition zone is an optimistic alternative to overcome the limitations of the Archie's equation in carbonate rocks. In general, effective porosity from NMR and neutron-density logs presented similar results. Nevertheless, NMR effective porosity was more accurate to regions with dolomitized and silicified carbonates and Mg-clays. In magnesian-clays interval, NMR effective porosity fitted two times better to the laboratory data than neutron-density effective porosity. So, in our analysis, the incorporation of NMR logs and its integration with conventional logs resulting in a hybrid approach provided a more assertive formation evaluation in the studied area, being essential its use in complex environments as presalt reservoirs.
      原文链接:
    • NSTL

    Fluid dynamics analysis and performance of polymer flow regulators for polymer flooding in multilayered reservoirs

    Paiva Rojas MiguelZanetti JoannaZanetti Stefano
    10页
    查看更多>>摘要： Polymer flooding, a high viscosity solution of water and polymer, is introduced as an enhancement of oil recovery methods which is pumped through injector wells to push the liquid hydrocarbon towards production wells. Nowadays, the polymer injections method through layers for different flow admissions has allowed the improvement of heterogeneous flow distribution and the oil recovery factor itself. However, choke valves are needed to get the flow control in admission layers. Nevertheless, any flow obstruction affects the polymer viscosity via mechanical degradation. The shear stress in a standard orifice waterflood regulator breaks down the polymer molecule, causing viscosity loss, and hence reducing the recovery factor properties. In order to avoid shear degradation, several proposal nonstandard regulators of flow/pressure control options have been selected. In this work, experimental and computational studies were made to evaluate the design performance of pressure regulators to inject a polymer solution. The intermittent flow patterns concept has gotten a superior performance. The experimental data from this shock absorber has shown the average viscosity loss being less than 10% and pressure drop up to 34.5 bar with a polymer concentration of up to 700 mg/L, high flowrate around 89 m3/d and average salinity water was used to prepare the polymer solution. It was confirmed that the computational results have achieved a good match with experimental data. These results will validate regulator design, and improve cost estimation, saving materials and additional water treatment facilities.
      原文链接:
    • NSTL